In practice, various valve actuating drives are known and in use. Besides widely employed electrical valve actuating drives, these also include in particular fluid-operated valve actuating drives (see, for example, EP 0665373 B1, EP 1418343 B1, EP 1593893 B1 and EP 2101061 A1). Such fluid-operated valve actuating drives may then comprise in particular, besides a hydraulically or pneumatically urged linear actuator, whose slide may be coupled directly or possibly via a mechanical converter with the input of the valve, a base unit provided with the control valves and/or other fluidic control means.
DE 9406760 U1 discloses a drive unit for valve, especially in shipbuilding. Therein there is provided a housing, which encloses an electric motor, a pump driven thereby, control elements and a hydraulic reservoir. The housing is connected to a swiveling drive, which comprises a piston with toothed rack and a shaft.
U.S. Pat. No. 4,647,003 A discloses an actuating device for the valve of a shutoff valve. The actuating device comprises a housing with a shaft mounted to rotate therein, capable of being coupled with the rotary shaft of the valve and having an associated pinion, with which the toothed rack meshes with at least one linear actuator constructed as a pneumatic cylinder. Depending on need, one or two pneumatic cylinders may be mounted on the housing. To supply the actuating device with compressed air, corresponding ports, to which the associated lines may be connected, are provided on the housing and the cylinders of the linear actuators.